As in many other fields, the arrival of digital technology has brought numerous innovations also to the field of visualization devices. For example, the normal cathode ray tube (CRT) displays, even though they can still offer high quality images, are now generally considered as too sensitive to disturbances and aesthetically unpleasant, heavy and cumbersome. In fact, the depth of the cathode ray tube increases proportionally to the diagonal size of the display.
For this reason, the CRT displays are today considered less attractive than the plasma or liquid crystal display (LCD) visualization devices which, on the contrary, can be made with a much greater diagonal screen size than that of a cathode ray display, while at the same time maintaining a reasonable depth. Therefore, they can be inserted easily into any environment, offering images without the deficiencies associated with CRT displays.
Today an innovative generation of visualization devices is being developed and experimented with which operate according to a working principle different from the working principles of the visualization devices made with LCD technology or plasma technology. These new generation visualization devices, which may be defined as “photonic” visualization devices, provide for the use of an innovative optic type technology which, to form images on the display, provides for the deflection of numerous modulated optical signals output from respective optical fibers fed by optical signal sources.
In these photonic visualization devices, a large sized screen is divided into a plurality (e.g., 6 or 12) of smaller sized screens or sub-screens, each comprised in a respective visualization unit.
With reference to FIG. 1, a visualization unit 1 is shown which includes a sub-screen 8 on which an image is formed by means of optical signals output from the end sections of two groups 9 of optical fibers. The end sections of each group 9 of optical fibers are inserted into suitable perforated mechanical supports 2.
The optical signals output from the two groups 9 of fibers are optically processed by first optical means, e.g., they are collimated by means of lenses 3, then deviated by reflecting elements 6 and then again collimated by further lenses 4 before being deviated by a rotating mirror which projects said beams on to the portion of the screen 8. Further optical processing means 7 (post-processing means) can be provided. on the optical path between the rotating mirror 5 and the portion of screen 8 on which the images are formed.
FIG. 2 shows a perspective view of a perforated mechanical support 2 into which the end sections of optical fibers 10, 11, 12 of a single group of fibers 9 are inserted. For simplicity, only three optical fibers 10, 11, 12 are shown in the figure while, in reality, the support 2 is intended to receive a much greater number of fibers.
The reference number 13 indicates a group of holes vertically aligned in three columns. Each column of the group 13 includes 32 holes for the insertion of a corresponding number of optical fibers. Thus, each support is intended to accommodate 96 end sections of respective optical fibers. The number of optical fibers necessary, therefore, for the manufacture of a photonic visualization device comprising twelve visualization units is equal to approximately 2300.
As a result of the large number of fibers, the manufacturing of a photonic visualization device has the disadvantage of being in practice, a very long, complex and delicate operation.
Apart from these practical difficulties, the presence of optical fibers poses a more serious problem due to the difficulty of using an automated industrial process for large scale production.